1. Field
The present invention provides a rail system for a powered pallet conveyor. Moreover, the present invention provides a process for operating a switch of a rail system for a powered pallet conveyor. The present invention uses a switch means for switching between m alternative travel pathways, wherein m≧2, and allowing the vehicle to continuously move across the switch after switching.
2. Description of Related Art
Powered pallet conveyors are known. Powered pallet conveyors may be used for loading or unloading trucks and trailers with product on pallets or in containers. Powered pallet conveyors may comprise a vehicle and a rail system which defines pathways on which the vehicle may travel.
Conventional rail systems for a powered pallet conveyor may comprise switch means for allowing the vehicle to travel on alternative pathways. U.S. Pat. No. 4,498,399 discloses a free line switch arrangement for power-and-free trolley conveyors wherein the free line comprises two rails. Two other types of switch means have been considered, namely a quadro switch and a rotation switch.
A quadro switch, as shown in FIG. 5 of the drawings, is operated by first positioning the vehicle on the switch so that pivotable wheels of the vehicle are placed on rotatable rail portions. Subsequently, the rotatable rail portions are rotated independently so that the wheels of the vehicle are oriented along and guided to the new travel pathway.
A rotation switch, as shown in FIG. 6 of the drawings, is also operated by first positioning the vehicle on the switch so that the vehicle may be rotated as a whole on a rotatable turntable. Subsequently, the rotatable turntable is rotated so that the vehicle is oriented along and guided to the new travel pathway.
Both switch means are unsatisfactory in that the vehicle cannot travel continuously across the switching means without stopping. As a consequence, the presence of a switching means results in a limitation of the maximum speed by which the powered pallet conveyor is capable of completing a task. Limitations imposed by the switching means are even greater in cases when more than one switching is required per travel of the powered pallet conveyor.
Furthermore, conventional switching means have significant space requirements. Moreover, vehicles subjected to frequent acceleration/deceleration suffer from increased wear and earlier failure so that maintenance costs are high.